/* Copyright © 2010 LPRM
Universidade Federal do Espírito Santo - RNP-GT CWTools

This file is part of JoinUs!.

JoinUs! is free software: you can redistribute it and/or modify
it under the terms of the GNU Lesser General Public License as published by
the Free Software Foundation, either version 3 of the License, or
(at your option) any later version.

JoinUs! is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU Lesser General Public License for more details.

You should have received a copy of the GNU Lesser General Public License
along with JoinUs!. If not, see <http://www.gnu.org/licenses/>. */
package br.ufes.inf.joinus;

//http://www.source-code.biz/snippets/java/Base64Coder.java.txt

public final class Base64 {
 private static char[] map1 = new char[64];
 static {
     int i=0;
     for (char c='A'; c<='Z'; c++) map1[i++] = c;
     for (char c='a'; c<='z'; c++) map1[i++] = c;
     for (char c='0'; c<='9'; c++) map1[i++] = c;
     map1[i++] = '+'; map1[i++] = '/';
 }

 private static byte[] map2 = new byte[128];
 static {
     for (int i=0; i<map2.length; i++) map2[i] = -1;
     for (int i=0; i<64; i++) map2[map1[i]] = (byte)i;
 }

 public static String encode (byte[] in)
 {
     int iLen = in.length;
     int oDataLen = (iLen*4+2)/3;       // output length without padding
     int oLen = ((iLen+2)/3)*4;         // output length including padding
     char[] out = new char[oLen];
     int ip = 0;
     int op = 0;
     while (ip < iLen) {
         int i0 = in[ip++] & 0xff;
         int i1 = ip < iLen ? in[ip++] & 0xff : 0;
         int i2 = ip < iLen ? in[ip++] & 0xff : 0;
         int o0 = i0 >>> 2;
         int o1 = ((i0 &   3) << 4) | (i1 >>> 4);
         int o2 = ((i1 & 0xf) << 2) | (i2 >>> 6);
         int o3 = i2 & 0x3F;
         out[op++] = map1[o0];
         out[op++] = map1[o1];
         out[op] = op < oDataLen ? map1[o2] : '='; op++;
         out[op] = op < oDataLen ? map1[o3] : '='; op++;
     }
     return new String(out);
 }

 public static byte[] decode (String s)
 {
     char[] in = s.toCharArray();
     int iLen = in.length;
     if (iLen%4 != 0) throw new IllegalArgumentException ("Length of Base64 encoded input string is not a multiple of 4.");
     while (iLen > 0 && in[iLen-1] == '=') iLen--;
     int oLen = (iLen*3) / 4;
     byte[] out = new byte[oLen];
     int ip = 0;
     int op = 0;
     while (ip < iLen) {
         int i0 = in[ip++];
         int i1 = in[ip++];
         int i2 = ip < iLen ? in[ip++] : 'A';
         int i3 = ip < iLen ? in[ip++] : 'A';
         if (i0 > 127 || i1 > 127 || i2 > 127 || i3 > 127)
             throw new IllegalArgumentException ("Illegal character in Base64 encoded data.");
         int b0 = map2[i0];
         int b1 = map2[i1];
         int b2 = map2[i2];
         int b3 = map2[i3];
         if (b0 < 0 || b1 < 0 || b2 < 0 || b3 < 0)
             throw new IllegalArgumentException ("Illegal character in Base64 encoded data.");
         int o0 = ( b0       <<2) | (b1>>>4);
         int o1 = ((b1 & 0xf)<<4) | (b2>>>2);
         int o2 = ((b2 &   3)<<6) |  b3;
         out[op++] = (byte)o0;
         if (op<oLen) out[op++] = (byte)o1;
         if (op<oLen) out[op++] = (byte)o2;
     }
     return out;
 }
}
